The first time Grace Shaw played her song Horses for a friend, “her face kind of scrunched up, and she just started crying”. It wasn’t an isolated reaction. When Horses was released, fans crowded into comments sections to report breaking down in tears the first time they heard the softly devastating pop song, one of Shaw’s first new releases as Mallrat in over two years.

Horses is mostly a song about returning home – Brisbane, in Shaw’s case, the city she left years ago but still “reps hard”. But its first verse explicitly references memories of catching the train home with her little sister Liv, who died last May, aged 21. Horses was written before that seismic loss, but it feels like the quiet howl of grief. “Can somebody let me out of myself?” Shaw begs in the refrain.

“The meaning that people took with it was grief,” Shaw says. “The way that I write lyrics, they often don’t make tangible sense, but … sometimes become crystal clear months or years down the line. It’s almost spooky.”

We’re sitting in a Sydney cafe just a couple of weeks after the release of Horses. It’s a strange time in Shaw’s life to be releasing music. Her second album, Light Hit My Face Like a Straight Right, out on 14 February, was completed a month before the death of her sister, but the lyrics frequently call out to a missing other, an angel who “could show up right now” and make Shaw so grateful. Light is a recurring motif, and the songs feel wrapped in a heavenly glow.

Shaw had been “really excited” about the album after its completion. Then Liv died, “and I couldn’t believe how little I cared about sharing music”. Instead, she says, she just wanted to hide under a rock. Grief melted over everything like a black sludge.

“The part of grief that I wasn’t expecting, that I actually felt the most frustrated with, was the inability to focus or problem solve or use my memory. It just felt like my brain was like an empty cave,” Shaw says. “And every time I would go to say something, I would get my words all muddled up. I couldn’t, for the life of me, remember what I was doing the day before. I wouldn’t be able to reply to emails, because the simplest question felt so overwhelming to think of a response to.”

Now seven months on from Liv’s death, Shaw says she is beginning to turn a corner. She is stoic if slightly reserved in our conversation, her first proper interview since her sister’s passing, but still wryly funny. She arrives wearing a badge from a vintage market that reads “I Love American Quarter Horses”. And Shaw really does love horses – her single is named after her memories of going to the Brisbane racetrack as a kid to offer her help caring for the animals there; the on-the-cheap hobby of “a horse girl without a horse”.

It’s now been 10 years since Shaw first started uploading music to SoundCloud as a teenager, songs she would now rather forget: “If you make me listen to those, it’s like medieval torture.” In the intervening decade she has collaborated with professional shit-stirrer Azealia Banks (“we haven’t talked in a little while, but I do love her”) and the Chainsmokers (“that felt so random and so off brand. But I don’t mean that in a derogatory way!”). She has performed on US late night TV and her debut album in 2022 landed at No 3 on the Aria charts.

Now 26, Shaw divides her time between Melbourne and LA. Brisbane just felt “too small and too slow” to stay in – not that she tolerates any slander of her home town from outsiders. “If someone from Melbourne went to Brisbane and said they hated it, I’d be like, you don’t know what you’re talking about.”

It was in Melbourne that Shaw made her second album, setting out to create something “less live-sounding” than her previous work. Interested in infusing warmth into electronic sounds, she collected a patchwork of samples, her unhurried vocals floating atop. She worked largely with producer and Troye Sivan collaborator Styalz Fuego, and only noticed afterwards how often she had written about light. In her lyrics, light is the soft glow of love, the bright rays emitted by someone wonderful, or, per the kickboxing reference of the album title, a clarifying shock that smacks her in the face.

Shaw’s songs have always possessed an unpretentious wisdom: a scrapbook of life “about everything and nothing”, she has said. She is rankled by bad poetry and bad lyrics. “There’s so much crap that’s so painfully earnest,” she laughs.

There are two poets, though, she does like – Leonard Cohen and her sister, who “was the most incredible writer”.

When we speak, Shaw is preparing to return to Queensland for Christmas. Losing her sister has unexpectedly reframed her complicated relationship with her home town. In the last few months, she says, “it’s been really nice to go back and spend proper time with my dad. It’s always emotional going home, but I do feel more relaxed about it now, somehow.”

As the light starts to break through the cracks of a difficult year, as Leonard Cohen might describe it, she is slowly rediscovering the joy of music.

“It was sad to go from being so excited to share this album to being like, I literally don’t want to share any part of me or talk to anyone. I have no interest. But that [feeling] is starting to dissipate.”

Seeing the reaction to Horses has helped.

“I forgot that … an important and beautiful part of [making music] is not just making it and keeping it to yourself, but sharing it,” she says. “It’s been a very weird year, but it’s beautiful that it’s being rounded off with this connection through this song. I feel very, very, very, very happy that I seem to have captured something magic.”

• Light Hit My Face Like a Straight Right by Mallrat is out 14 February

Mallrat’s songs to live by

Each month we ask our headline act to share the songs that have accompanied them through love, life, lust and death.

What was the best year for music, and what five songs prove it?

I loved 2012 for a lot of reasons, including how clunky the convergence of pop and EDM was, and the fact that we got Lana Del Rey’s debut album Born to Die. The songs: Call Me Maybe by Carly Rae Jepsen, Video Games by Lana Del Rey, Bounce by Calvin Harris (feat. Kelis), Levels by Avicii, and Holdin On by Flume.

What music do you clean the house to?

Drop the Pressure by Mylo. Dancing while I clean keeps me focused!

What’s the song you wish you wrote?

Fade Into You by Mazzy Star.

What is the last song you sang in the shower?

Woah, this made me realise I haven’t sung in the shower for a long time. That’s kind of sad. I think it was this traditional Irish song called Mo Ghile Mear.

What is the song you have listened to the most times this year?

Diet Pepsi by Addison Rae.

What is your go-to karaoke song, and why?

My friend Sycco and I love to sing Suddenly I See by KT Tunstall and we turn it into a duet.

What is a song you loved as a teenager?

This question just sent me down a cute wormhole. I went and found a playlist I made in 2013; I would have been 14 years old. It rocks! There’s lots of Azealia Banks, Florence + the Machine, Lana Del Rey, Two Door Cinema Club, Flume and Grimes. I thought I was a complete dag when I was a teenager but maybe I was a little bit cool.